Alert archive / Louisiana / Severe Thunderstorm Warnings in 2007

Severe Thunderstorm Warning 158, NWS New Orleans, LA

November 21, 2007Iberville Parish, Pointe Coupee Parish, West Baton Rouge Parish, Louisiana

NWS New Orleans, LA issued this severe thunderstorm warning at Nov 21, 2007, 8:32 PM CST for Iberville Parish, Pointe Coupee Parish, West Baton Rouge Parish, Louisiana. It was in force for 28 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Nov 21, 2007, 8:32 PM CST (02:32 UTC)
Expired: Nov 21, 2007, 9:00 PM CST
In force: 28 min
Issued by: NWS New Orleans, LA
Area: Storm-based polygon

Counties Iberville Parish, LA, Pointe Coupee Parish, LA, West Baton Rouge Parish, LA

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Nov 21, 5:29 PM CST	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 2.5 hours before the alert went out and 175 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1748 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 652 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 91 m²/s²
0-3 km storm-relative helicity: 104 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 3.3

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS New Orleans, LA wrote its last area forecast discussion before this severe thunderstorm warning went out at Nov 21, 4:10 PM CST, 4 hours 22 minutes earlier.

Area forecast discussion, Nov 21, 4:10 PM CST, 4 hours 22 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
410 PM CST WED NOV 21 2007

.DISCUSSION
MAIN FORECAST CONCERNS CONTINUE TO CENTER AROUND CONVECTION
TONIGHT AND AGAIN SUNDAY INTO EARLY MONDAY. THE SCATTERED
CONVECTION THAT DEVELOP ACROSS THE FORECAST AREA THIS AFTERNOON AND
PRODUCED ISOLATED HAIL AND WIND DAMAGE IN SOUTHWEST MISSISSIPPI IS
BEGINNING TO MOVE OUT OF THE AREA AS IT PUSHES OFF TO THE EAST
NORTHEAST. HOWEVER ADDITIONAL CONVECTION IS EXPECTED OVERNIGHT AS
THE CONVECTION CURRENTLY OVER EAST TEXAS AND WESTERN LOUISIANA
PROGRESSES TO THE EAST. THE CONVECTION HAS BEEN ENHANCED TODAY BY
A JET MAX MOVING AROUND THE BASE OF AN UPPER TROUGH TRAVERSING THE
CENTRAL PLAINS...A WEAK DISTURBANCE MOVING OUT OF COASTAL TEXAS
AS WELL AS RATHER SHEARED WIND ENVIRONMENT. IT APPEARS THAT THE
BEST DYNAMICS WILL REMAIN NORTH OF THE FORECAST AREA TONIGHT WITH
THIS SYSTEM...HOWEVER ISOLATED STRONG TO SEVERE THUNDERSTORMS WILL
BE POSSIBLE...ESPECIALLY ACROSS THE NORTH ZONES. A STRONG COLD
FRONT ASSOCIATED WITH THIS SYSTEM AND CURRENTLY MOVING ACROSS
ARKANSAS AND NORTHEAST TEXAS WILL PUSH ACROSS THE FORECAST AREA
AFTER MIDNIGHT TONIGHT AND THROUGH EARLY THURSDAY MORNING. LINGERING
CONVECTION CAN BE EXPECTED ACROSS COASTAL AREAS AND THE ADJACENT
COASTAL WATERS THROUGH THURSDAY MORNING. IN THE WAKE OF THIS FRONT MUCH
COOLER CONDITIONS WILL PREVAIL WITH HIGH ONLY IN THE 50S AND 60S
THURSDAY INTO SATURDAY. RAIN WILL MOVE BACK INTO THE PICTURE ON
SATURDAY AS WARM AIR ADVECTION RETURNS TO THE GULF COAST REGION.
ANOTHER SYSTEM...THIS ONE QUITE VIGOROUS...IS FORECAST TO EJECT
OUT OF THE SOUTHWEST CONUS OR NORTHERN MEXICO LATE OVER THE
WEEKEND AND MOVE ACROSS TEXAS/SOUTHERN PLAINS AND THE LOWER
MISSISSIPPI VALLEY LATE SUNDAY INTO MONDAY. CYCLOGENESIS IS
FORECAST TO TAKE PLACE OVER THE NORTHWEST GULF AS THIS UPPER
TROUGH APPROACHES AND BEGINS TO TAKE ON A NEGATIVE TILT. THIS LOW
IS THEN FORECAST TO TRACK NORTHEAST ACROSS LOUISIANA AND
MISSISSIPPI LATE SUNDAY AND SUNDAY NIGHT. AS IT LOOKS NOW...THERE
WILL BE A THREAT OF SEVERE THUNDERSTORMS AND POSSIBLY HEAVY RAIN
SUNDAY AND SUNDAY NIGHT ALTHOUGH THE TIMING WITH THIS SYSTEM IS A
BIT UNCERTAIN.

&&

.AVIATION...
MVFR TO OCCASIONAL IFR CONDITIONS ARE EXPECTED THROUGH TONIGHT DUE
TO CEILING AND OCCASIONAL CONVECTION.

&&

.MARINE...
SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED TO DEVELOP BEHIND THE
COLD FRONT DURING THE DAY THURSDAY ACROSS THE GULF COASTAL WATERS
AND OVER LAKES PONTCHARTRAIN AND MAUREPAS THURSDAY NIGHT. SMALL
CRAFT CONDITIONS WILL PERSIST OVER THE GULF COASTAL WATERS THROUGH
FRIDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  51  56  37  56 /  70  20  10  10
BTR  53  59  39  58 /  70  20  10  10
MSY  59  62  45  58 /  60  30  10  10
GPT  58  64  41  58 /  60  40  10  10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&

11

Hazardous weather outlook, Nov 21, 7:21 PM CST, 1 hour 11 minutes before

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In the hours before

Local storm report, Nov 21, 2:46 PM CST, 5 hours 46 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
246 PM CST WED NOV 21 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0240 PM     HAIL             OSYKA                   31.01N 90.47W
11/21/2007  E1.75 INCH       PIKE               MS   LAW ENFORCEMENT

            STATE POLICE REPORTED GOLF BALL SIZE HAIL ON INTERSTATE
            55 AT EXIT 1.

&&

92/JSS

Local storm report, Nov 21, 3:25 PM CST, 5 hours 7 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
325 PM CST WED NOV 21 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0315 PM     HAIL             5 S TYLERTOWN           31.04N 90.14W
11/21/2007  E0.75 INCH       WALTHALL           MS   LAW ENFORCEMENT

            PENNY SIZE HAIL COVERING GROUND.

&&

Local storm report, Nov 21, 3:41 PM CST, 4 hours 51 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NEW ORLEANS LA
341 PM CST WED NOV 21 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0320 PM     TSTM WND GST     3 SE TYLERTOWN          31.09N 90.11W
11/21/2007  E0.00 MPH        WALTHALL           MS   LAW ENFORCEMENT

            SEVERAL TREES BLOWN DOWN NEAR THE COMMUNITY OF LEXIE.

0330 PM     TSTM WND DMG     SE TYLERTOWN            31.12N 90.14W
11/21/2007                   WALTHALL           MS   LAW ENFORCEMENT

            SEVERAL TREES BLOWN DOWN ON HIGHWAY 48.

&&

Local storm report, Nov 21, 8:18 PM CST, 14 minutes before

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Special weather statement, Nov 21, 8:26 PM CST, 6 minutes before

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The office that day

Everything else NWS New Orleans, LA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Nov 21, 7:33 PM CST	Severe Thunderstorm Warning	LIX	Pointe Coupee, West Feliciana	42 min
Nov 21, 9:03 PM CST	Severe Thunderstorm Warning	LIX	Saint Helena	14 min
Nov 21, 9:48 PM CST	Special Marine Warning	LIX		57 min
Nov 21, 7:03 PM CST	Severe Thunderstorm Warning	LIX	Wilkinson	42 min
Nov 21, 7:46 PM CST	Severe Thunderstorm Warning	LIX	Amite, Wilkinson	29 min

Nearby

Severe Thunderstorm Warnings in Louisiana, 2007 Every severe thunderstorm warning in 2007

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.